Spring AOP源码分析
https://cloud.tencent.com/developer/article/1512235
https://www.cnblogs.com/wangshen31/p/9379197.html
https://blog.csdn.net/woshilijiuyi/article/details/83934407
总结
- spring容器在初始化时，进行applyBeanPostProcessorsAfterInitialization处理
- 调用AbstractAutoProxyCreator的postProcessAfterInitialization方法
- 当处理满足@Pointcut中条件的Bean时，getAdvicesAndAdvisorsForBean不为null，执行生成Proxy逻辑
- 当想调用被代理类中方法时，Proxy类进行代理；实现横切面逻辑
生成代理类
如Pointcut在controller中时
@Pointcut("execution(* com.java.study.controller.*.*(..))")
public void logPointcut() { }
则在预实例化时，在AbstractAutowireCapableBeanFactory中doCreateBean方法对Bean进行实例化、属性注入和初始化
Object exposedObject = bean;
try {
populateBean(beanName, mbd, instanceWrapper);
exposedObject = initializeBean(beanName, exposedObject, mbd);
}
初始化时,调用applyBeanPostProcessorsAfterInitialization方法
protected Object initializeBean(String beanName, Object bean, @Nullable RootBeanDefinition mbd) {
......
if (mbd == null || !mbd.isSynthetic()) {
wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);
}
return wrappedBean;
}
其中processor为AnnotationAwareAspectJAutoProxyCreator时
@Override
public Object applyBeanPostProcessorsAfterInitialization(Object existingBean, String beanName)
throws BeansException {
Object result = existingBean;
for (BeanPostProcessor processor : getBeanPostProcessors()) {
//AnnotationAwareAspectJAutoProxyCreator
Object current = processor.postProcessAfterInitialization(result, beanName);
if (current == null) {
return result;
}
result = current;
}
return result;
}
因AnnotationAwareAspectJAutoProxyCreator extends AspectJAwareAdvisorAutoProxyCreator ，AspectJAwareAdvisorAutoProxyCreator extends AbstractAdvisorAutoProxyCreator，AbstractAdvisorAutoProxyCreator extends AbstractAutoProxyCreator，调父类AbstractAutoProxyCreator的postProcessAfterInitialization方法
@Override
public Object postProcessAfterInitialization(@Nullable Object bean, String beanName) {
if (bean != null) {
Object cacheKey = getCacheKey(bean.getClass(), beanName);
if (this.earlyProxyReferences.remove(cacheKey) != bean) {
return wrapIfNecessary(bean, beanName, cacheKey);
}
}
return bean;
}
调用AbstractAutoProxyCreator#wrapIfNecessary（）
protected Object wrapIfNecessary(Object bean, String beanName, Object cacheKey) {
if (StringUtils.hasLength(beanName) && this.targetSourcedBeans.contains(beanName)) {
return bean;
}
if (Boolean.FALSE.equals(this.advisedBeans.get(cacheKey))) {
return bean;
}
if (isInfrastructureClass(bean.getClass()) || shouldSkip(bean.getClass(), beanName)) {
this.advisedBeans.put(cacheKey, Boolean.FALSE);
return bean;
}
// Create proxy if we have advice.
Object[] specificInterceptors = getAdvicesAndAdvisorsForBean(bean.getClass(), beanName, null);
if (specificInterceptors != DO_NOT_PROXY) {
this.advisedBeans.put(cacheKey, Boolean.TRUE);
Object proxy = createProxy(
bean.getClass(), beanName, specificInterceptors, new SingletonTargetSource(bean));
this.proxyTypes.put(cacheKey, proxy.getClass());
return proxy;
}
this.advisedBeans.put(cacheKey, Boolean.FALSE);
return bean;
}
最后返回specificInterceptors不为null，开始创建Proxy。调用AbstractAutoProxyCreator#createProxy(),set
advisors和targetSource
protected Object createProxy(Class<?> beanClass, @Nullable String beanName,
@Nullable Object[] specificInterceptors, TargetSource targetSource) {
ProxyFactory proxyFactory = new ProxyFactory();
proxyFactory.copyFrom(this);
......
Advisor[] advisors = buildAdvisors(beanName, specificInterceptors);
proxyFactory.addAdvisors(advisors);
proxyFactory.setTargetSource(targetSource);
customizeProxyFactory(proxyFactory);
......
return proxyFactory.getProxy(getProxyClassLoader());
}
ProxyCreatorSupport#createAopProxy() --> DefaultAopProxyFactory#createAopProxy(),判断走JDK动态代理还是CGLIB代理，此时由于代理是类，返回new ObjenesisCglibAopProxy(config)
@Override
public AopProxy createAopProxy(AdvisedSupport config) throws AopConfigException {
if (config.isOptimize() || config.isProxyTargetClass() || hasNoUserSuppliedProxyInterfaces(config)) {
Class<?> targetClass = config.getTargetClass();
if (targetClass == null) {
throw new AopConfigException("TargetSource cannot determine target class: " +
"Either an interface or a target is required for proxy creation.");
}
if (targetClass.isInterface() || Proxy.isProxyClass(targetClass)) {
return new JdkDynamicAopProxy(config);
}
return new ObjenesisCglibAopProxy(config);
}
else {
return new JdkDynamicAopProxy(config);
}
}
走CglibAopProxy#getProxy()
@Override
public Object getProxy(@Nullable ClassLoader classLoader) {
if (logger.isTraceEnabled()) {
logger.trace("Creating CGLIB proxy: " + this.advised.getTargetSource());
}
try {
Class<?> rootClass = this.advised.getTargetClass();
Assert.state(rootClass != null, "Target class must be available for creating a CGLIB proxy");
Class<?> proxySuperClass = rootClass;
......
// Validate the class, writing log messages as necessary.
validateClassIfNecessary(proxySuperClass, classLoader);
// Configure CGLIB Enhancer...
Enhancer enhancer = createEnhancer();
if (classLoader != null) {
enhancer.setClassLoader(classLoader);
if (classLoader instanceof SmartClassLoader &&
((SmartClassLoader) classLoader).isClassReloadable(proxySuperClass)) {
enhancer.setUseCache(false);
}
}
enhancer.setSuperclass(proxySuperClass);
enhancer.setInterfaces(AopProxyUtils.completeProxiedInterfaces(this.advised));
enhancer.setNamingPolicy(SpringNamingPolicy.INSTANCE);
enhancer.setStrategy(new ClassLoaderAwareGeneratorStrategy(classLoader));
Callback[] callbacks = getCallbacks(rootClass);
Class<?>[] types = new Class<?>[callbacks.length];
for (int x = 0; x < types.length; x++) {
types[x] = callbacks[x].getClass();
}
// fixedInterceptorMap only populated at this point, after getCallbacks call above
enhancer.setCallbackFilter(new ProxyCallbackFilter(
this.advised.getConfigurationOnlyCopy(), this.fixedInterceptorMap, this.fixedInterceptorOffset));
enhancer.setCallbackTypes(types);
// Generate the proxy class and create a proxy instance.
return createProxyClassAndInstance(enhancer, callbacks);
}
......
}
protected Object createProxyClassAndInstance(Enhancer enhancer, Callback[] callbacks) {
enhancer.setInterceptDuringConstruction(false);
enhancer.setCallbacks(callbacks);
return (this.constructorArgs != null && this.constructorArgTypes != null ?
enhancer.create(this.constructorArgTypes, this.constructorArgs) :
enhancer.create());
}
生成Advisor过程
调用链：
AbstractApplicationContext#onRefresh() --> ServletWebServerApplicationContext#onRefresh() -->
ServletWebServerApplicationContext#createWebServer() -->ServletWebServerApplicationContext#getWebServerFactory -->DefaultListableBeanFactory#getBeanNamesForType() -->DefaultListableBeanFactory#doGetBeanNamesForType() -->AbstractBeanFactory#isTypeMatch() -->AbstractAutowireCapableBeanFactory#getTypeForFactoryBean() -->AbstractAutowireCapableBeanFactory#getSingletonFactoryBeanForTypeCheck() -->AbstractAutowireCapableBeanFactory#resolveBeforeInstantiation() -->AbstractAutowireCapableBeanFactory#applyBeanPostProcessorsBeforeInstantiation()-->AbstractAutoProxyCreator#postProcessBeforeInstantiation() -->AspectJAwareAdvisorAutoProxyCreator#shouldSkip()-->AnnotationAwareAspectJAutoProxyCreator#findCandidateAdvisors() --> BeanFactoryAspectJAdvisorsBuilder#buildAspectJAdvisors()
- cachedAdvisorBeanNames赋值过程
在AnnotationAwareAspectJAutoProxyCreator#findCandidateAdvisors()时，调用super.findCandidateAdvisors();
@Override
protected List<Advisor> findCandidateAdvisors() {
// Add all the Spring advisors found according to superclass rules.
List<Advisor> advisors = super.findCandidateAdvisors();
// Build Advisors for all AspectJ aspects in the bean factory.
if (this.aspectJAdvisorsBuilder != null) {
advisors.addAll(this.aspectJAdvisorsBuilder.buildAspectJAdvisors());
}
return advisors;
}
然后调用BeanFactoryAdvisorRetrievalHelper#findAdvisorBeans()时，this.cachedAdvisorBeanNames = advisorNames;指向String数组，不再为null
public List<Advisor> findAdvisorBeans() {
// Determine list of advisor bean names, if not cached already.
String[] advisorNames = this.cachedAdvisorBeanNames;
if (advisorNames == null) {
// Do not initialize FactoryBeans here: We need to leave all regular beans
// uninitialized to let the auto-proxy creator apply to them!
advisorNames = BeanFactoryUtils.beanNamesForTypeIncludingAncestors(
this.beanFactory, Advisor.class, true, false);
this.cachedAdvisorBeanNames = advisorNames;
}
}
- 生成List
过程
buildAspectJAdvisors方法先获取所有beanNames
String[] beanNames = BeanFactoryUtils.beanNamesForTypeIncludingAncestors(this.beanFactory, Object.class, true, false);
当执行到有@Aspect注解的AopLog时,isAspect为true，进行处理
//true
if (this.advisorFactory.isAspect(beanType)) {
......
}
@Override
public boolean isAspect(Class<?> clazz) {
return (hasAspectAnnotation(clazz) && !compiledByAjc(clazz));
}
获取切面中所有advice
List<Advisor> classAdvisors = this.advisorFactory.getAdvisors(factory);
获取List过程
调用getAdvicesAndAdvisorsForBean（）
@Override
@Nullable
protected Object[] getAdvicesAndAdvisorsForBean(
Class<?> beanClass, String beanName, @Nullable TargetSource targetSource) {
List<Advisor> advisors = findEligibleAdvisors(beanClass, beanName);
if (advisors.isEmpty()) {
return DO_NOT_PROXY;
}
return advisors.toArray();
}
调用findEligibleAdvisors（）
protected List<Advisor> findEligibleAdvisors(Class<?> beanClass, String beanName) {
List<Advisor> candidateAdvisors = findCandidateAdvisors();
List<Advisor> eligibleAdvisors = findAdvisorsThatCanApply(candidateAdvisors, beanClass, beanName);
extendAdvisors(eligibleAdvisors);
if (!eligibleAdvisors.isEmpty()) {
eligibleAdvisors = sortAdvisors(eligibleAdvisors);
}
return eligibleAdvisors;
}
由于BeanFactoryAdvisorRetrievalHelper#findAdvisorBeans()中cachedAdvisorBeanNames不为null，结果返回new ArrayList<>()
@Override
protected List<Advisor> findCandidateAdvisors() {
// Add all the Spring advisors found according to superclass rules.
List<Advisor> advisors = super.findCandidateAdvisors();
// Build Advisors for all AspectJ aspects in the bean factory.
if (this.aspectJAdvisorsBuilder != null) {
advisors.addAll(this.aspectJAdvisorsBuilder.buildAspectJAdvisors());
}
return advisors;
}
执行BeanFactoryAspectJAdvisorsBuilder#buildAspectJAdvisors（）,直接在缓存中取出advisor
public List<Advisor> buildAspectJAdvisors() {
List<String> aspectNames = this.aspectBeanNames;
......
List<Advisor> advisors = new ArrayList<>();
for (String aspectName : aspectNames) {
List<Advisor> cachedAdvisors = this.advisorsCache.get(aspectName);
if (cachedAdvisors != null) {
//执行
advisors.addAll(cachedAdvisors);
}
else {
MetadataAwareAspectInstanceFactory factory = this.aspectFactoryCache.get(aspectName);
advisors.addAll(this.advisorFactory.getAdvisors(factory));
}
}
return advisors;
}
TODO
SpringMVC源码
